Breathable multi-component exhaust insulation system

ABSTRACT

A breathable, multi-layer exhaust insulation system is provided. The system includes a multi-layer sleeve, wherein the first layer, which is positioned adjacent the exhaust system pipes, is a braided sleeve which may be constructed from high-temperature resistant materials such as e-glass, s-glass, silica or ceramic. Additional braided layers of material may be included, as well. An outside cover of material is preferably a circular knitted fabric that contains glass fibers and resin-based fibers. The knitted fabric forms a tube on the outside of the insulating layers, and may be formed from a core spun yarn, which includes a glass filament core and a high-melt fiber on the wrap. Optionally, the system may also include a perforated or unperforated metal foil layer and/or a tape wrap, and the various components may be configured as desired.

BACKGROUND OF THE INVENTION

The present invention relates generally to insulation for exhaustsystems and other types of pipe systems that transport hot gases andother hot fluid materials. More specifically, the present inventionrelates to a multi-component sleeve that may be used, among otherthings, to fit exhaust systems on vehicles generally and large trucks inparticular.

Heretofore, various insulation systems have been used to insulateautomotive and industrial exhaust systems. Exhaust insulation systemsare used to maintain high temperature of exhaust gases in order toprovide more efficient and complete combustion of fuels, and to protectsurrounding components from the high exhaust temperatures. Additionally,maintaining high exhaust temperatures tends to increase the velocity ofthe exhaust gases through the system, which allows the engine cylinderto more fully evacuate and aids in the emission control processes. Onlarge bore diesel trucks, insulating the exhaust system has been shownto improve the performance of the emission control system located in theexhaust stream system.

U.S. Pat. No. 6,610,928 discloses a sleeve for providing thermalinsulation to elongated substrates, formed from a composite sheet havinga tough, resilient reinforcing layer to which a metallic reflectivelayer is attached on one side and a fibrous, non-woven insulative layeris attached on the opposed side. The sleeve includes a seam, formedlengthwise along the sleeve in spaced relation to the reverse fold,defining a central space for receiving elongated substrates.

U.S. Pat. No. 6,978,643 is directed to a multilayer sleeve forinsulating or protecting elongated substrates, wherein the sleeve iscontinuously knitted in different sections integrally joined end to end,the sections being formed of different filamentary members chosen fordesired characteristics. The sleeves are formed into the multilayerconfiguration by reverse folding the sleeves inwardly to place onesection coaxially within another.

U.S. Pat. No. 5,134,846 discloses a cover for insulating exhaust systemsof internal combustion engines comprising a tubular shaped layer ofinsulating material circumscribingly engaging the exhaust system and aflexible metal sleeve for protecting the insulating material and holdingthe insulating material against the exhaust system. The cover is held inplace by hose clamps or tie wraps.

U.S. Pat. No. 5,092,122 is directed to a means and method for insulatingautomotive exhaust pipes by sliding a flexible insulated tube over theexhaust pipe. The tube comprises concentrically arranged inner and outercorrugated stainless steel tubes, with the annulus between thecorrugated tubes filled with refractory fiber insulation.

U.S. Pat. No. 5,617,900 includes a thermally insulative sleeve with aseamless, hollow flexibly resilient inner tubular member woven of strandmaterial including at least one metal wire strand, a separate, integral,at least essentially unbroken, metal surface member applied over theinner tubular member extending along and at least essentially completelysurrounding the inner tubular member and a flexible outer cover alsowoven of strand material extending along and completely around the innertubular member and metal surfaced member securing the metal surfacemember with the inner tubular member and offering some degree ofprotection. The inner tubular member may be knit from wire or from acombination of wire and glass fiber yarn, the latter providing somethermal insulative protection.

U.S. Patent Application Publication No. 2002/0168488 discloses aprotective sleeve for covering elongated substrates, wherein the sleeveis knitted from a combination of first and second filamentary fibershaving different properties from one another. The filamentary membersare plated so that the filamentary members with properties compatiblewith the substrate are positioned predominantly on the inner surface ofthe sleeve facing and engaging the substrate. Filament propertiesinclude heat resistance, high tensile strength, resistance to abrasion,chemical attack and damping capability. The sleeve includes ribsintegrally knitted lengthwise along the sleeve to form insulating airpockets, and the ends of the sleeve are finished with welts to preventunraveling.

Unfortunately, many of these prior art exhaust insulation sleeves sufferfrom various drawbacks. Some are expensive to manufacture and difficultto install on exhaust systems. Some require specialized tooling for eachdistinct pipe geometry. Many do not provide sufficient breathability, sothat when the insulation is exposed to water and rain, the water soaksinto the insulation and does not dry quickly, which leads to rust andcorrosion within the exhaust system. Because these type systems aresubject to large temperature fluctuations, sometimes more than a 1000°F., from start-up to upper operating temperatures and fluctuationswithin operating temperatures, there is a need for insulating systems tobreathe to some degree. Further, particularly in colder climates andcoastal climates, salt from the roads can infiltrate the insulationsystem and accelerate corrosion of the system. Moreover, many of theinsulation sleeves and systems are made from materials that do notmaintain their structural integrity over time due to wear and tear, andfurther degrade from the exposure to high temperatures associated withexhaust systems. Therefore, it would be desirable to provide abreathable, tough, resilient insulating system that can withstand therigors of exposure to high temperatures, salt, water, and general wearand tear, which is inexpensive and easy to manufacture and install.

BRIEF SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a breathable,multi-layer exhaust insulation system is provided. In one aspect of theinvention, the system includes a multi-layer sleeve, wherein the firstlayer, which is positioned adjacent the exhaust system pipes, is abraided, knit or woven sleeve which may be constructed fromhigh-temperature resistant materials such as e-glass, s-glass, silica orceramic. Additional braided layers of material may be included, as well.An outside cover of material may be a circular knitted fabric thatcontains glass fibers, reinforcing fibers and resin-based fibers. Theknitted fabric forms a tube on the outside of the insulating layers,which is made by knitting the tube or knitting a fabric and cutting andsewing the tube. The knitted tube may be formed from a core spun yarn,which includes a glass filament core and a high-melt fiber on the wrapalong with stainless steel reinforcing fibers. The wrap can be made fromresin type fibers including Poly(p-phenylene sulfide) PPS (sold underthe trade name Ryton), Polyetherimide (PEI) sold under the trade nameUltem, Polyether ether ketone (PEEK), Polysulfone (PES), Pol hthalamide(PPA), nylon, polyester, or polypropylene.

Optionally, a metal foil layer (or multiple metal foil layers) may bedisposed between the braided insulation and the knit cover to improveinsulation performance and reduce the rate of fluid adsorption into theinsulation layers. The metal foil layer(s) may be made of aluminum,fiberglass reinforced aluminum, stainless steel, nickel, copper or tin,although any suitable metal foil may be used. Additionally, the metalfoil layer(s) may be perforated or unperforated. The perforationsenhance breathability of the insulating sleeve.

In one preferred embodiment of the present invention, the insulatingsleeve includes a first layer of a braided silica sleeve adjacent theexhaust system pipes, then two layers of braided e-glass for insulation,and an outer layer of a PPS/glass cover treated with a fluorocarbon sewninto a tubular sleeve using a glass/stainless steel sewing thread and asafety lock stitch. Each end of the insulation is secured using astainless steel band clamp or other suitable attachment means.

Additionally, it may be desirable to include a high-temperature film,which is disposed about an outer side of the metal foil layer, in orderto protect the metal foil layer from oxidation. Suitablehigh-temperature films may include polyimide (commonly referred to as“PI,” and commercially available under the trade name Kapton), PEI, PPS,PEEK, PPA, silicone, nylon, polyester or polypropolene.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 is a perspective view of one embodiment of a breathablemulti-component insulation system in accordance with the presentinvention;

FIG. 2 is a perspective cut-away view of one embodiment of a breathablemulti-component insulation system in accordance with the presentinvention;

FIG. 3 is a perspective cut-away view of another embodiment of abreathable multi-component insulation system in accordance with thepresent invention;

FIG. 4 is a perspective cut-away view of another embodiment of abreathable multi-component insulation system in accordance with thepresent invention;

FIG. 5 is a perspective cut-away view of another embodiment of abreathable multi-component insulation system in accordance with thepresent invention; and

FIG. 6 is a perspective cut-away view of another embodiment of abreathable multi-component insulation system in accordance with thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention includes, in a first embodiment, a breathable,multi-layer exhaust insulation system, as shown in FIGS. 1-6. Theexhaust insulation system includes a multi-layer sleeve 12, which cantake one of several forms, and include a variety of components. Theexhaust insulation system sleeve 12 is positioned about an outer side ofa pipe 10, or the like.

Component Layers

The inner layer 14 or layers of the sleeve may include a braided or knitmaterial made from high-temperature resistant materials including, butnot limited to e-glass, s-glass, silica or ceramic. Braiding is thepreferred textile construction of the inner layer, due to the fact thatit is possible to deliver thicker profiles than knitted materials. Inone preferred embodiment, the inner layer of silica is about 1/16″ thickand the glass layers are 0.2 inches thick. Further, another advantage ofusing braided material is that stretching the braided layer along thelength of the exhaust pipe upon installation tends to tighten thebraided layer down around the pipe 10 or underlying layer along thestraight and bent sections. Depending upon the application andspecification of the desired insulating sleeve 12, a single braidedlayer may be used, or multiple braided layers may be used. Additionally,the inner layer 14 of the sleeve 12, which comes into contact with theunderlying exhaust pipe 10, is preferably made from this braided layer,although other textile constructions may be used, as desired.

Optionally, a metal foil layer 16 may be disposed on the outside of thebraided layer(s), as shown in FIGS. 3 and 4. The metal foil may includeperforations, as shown in FIG. 4, in order to enhance breathability ofthe sleeve 12, which facilitates drying of the sleeve 12 after exposureto water or other liquid. The metal foil layer 16 may be formed fromaluminum, fiberglass reinforced aluminum, stainless steel, nickel,copper or tin, although it should be understood that any other suitablemetal foil may be used, if such a layer is desired. The metal foil layer16 serves to improve the insulation performance of the insulation sleeve12 and to reduce the rate of fluid adsorption into the insulationlayers. Additionally, it may be desirable to include a high-temperaturefilm, which is disposed about an outer side of the metal foil layer 16,in order to protect the metal foil layer 16 from oxidation. Suitablehigh-temperature films may include polyimide (PI) (commerciallyavailable under the trade name Kapton), PEI, PPS, PEEK, PPA, silicone,nylon, polyester or polypropolene. Optionally, a tape wrap 18 may bewrapped around the metal foil layer 16, as shown in FIG. 5, primarily toprevent salt and other corrosive materials from penetrating through theinsulative sleeve. One example of a tape wrap 18 is sold by DuPont,under the tradename of KAPTON™.

An outer cover layer 20 is preferably a knitted tube that fits aroundthe other, underlying layers. Generally, the outer cover layer 20comprises a knitted fabric that includes glass fibers and resin-basedfibers. Thermoplastic fibers may include polyester, nylon, PPS orULTEM™. The outer cover layer 20 knitted tube is preferably made from acore spun yarn, which includes a glass filament core and a high meltfiber wrapped around the glass filament core further twisted with astainless steel yarn. The wrap may be made from PPS (Ryton). The outercover layer 20 knitted tube may be disposed on the outside of theunderlying insulating layers by knitting the tube around the underlyinglayers, or by knitting the tube and cutting and sewing the outer coverlayer 20 knitted tube around the underlying layers of the sleeve.Additionally, the outer cover layer 20 may be treated with afluorocarbon, such as Zonyl from Dupont, in order to reduce thepenetration of fluids into the cover and the overall system.

Preferred Construction

In one preferred embodiment, the inner layer 14 adjacent the exhaustpipe 10 is a braided silica sleeve. The next two layers 22, 24 outsideof the inner braided silica layer are each preferably formed frombraided e-glass for insulation. The outer cover layer 20 is a3-dimensional, spacer fabric in which a single fabric is comprised ofthree layers or portions, an inner portion, middle portion and outerportion. The outer portion preferably includes PPS/glass and stainlesssteel yarn. The inner portion is preferably made from glass fibers andthe middle portion is made from PPS/glass/stainless steel yarns. Theouter cover layer 20 may be treated with a fluorocarbon, and may be sewninto a tubular sleeve, preferably by using a glass/stainless steelsewing thread and a safety lock stitch. Stainless steel band clamps 32are the preferred means for affixing the exhaust insulation sleeve 12 tothe pipe 10, although other attachment means may be used.

Alternatively, another preferred embodiment includes a layer offiberglass reinforced aluminum 34 disposed between the outer cover layer20 and the underlying braided e-glass layer 24. Additionally, this layerof fiberglass reinforced aluminum may include a series of perforations26 throughout that layer, in order to enhance the breathability of thesleeve. One other alternative embodiment includes the use of a tape wrap18, such as the prior-mentioned DuPont product KAPTON™, which is wrappedaround the outside of the fiberglass reinforced aluminum layer set forthabove, as shown in FIGS. 5 and 6.

Installation

To install the sleeve 12 on a section of exhaust pipe 10, the layers areadded by sliding the inner layer 14 onto the pipe, then sliding the nextlayer 22 over the underlying layer 14, and continuing in this fashionuntil the only remaining layer to install is the outer cover layer 20.For the underlying braided layers, an installer may optionally stretchthem along the length of the section of pipe 10 in order to tighten themdown to the pipe 20 or underlying layers. The outer cover layer 20 maythen be slipped over the underlying layers. The system can also bepreassembled and then slipped onto the pipe 10 as a single component.The outer cover layer 20 may be knitted and finished as a flat fabricand then cut and sewn into the correctly sized tube. The outer layer 20may also be knit to the correct size diameter and used in this form.Then the clamps 32 are applied to each end of the sleeve 12, in order tosecure it to the pipe 10, and the entire apparatus is placed into anoven, preferably at about 560° F. for one hour, for curing. The outerlayer 20 becomes dimensionally stable and significantly stiffer as aresult of the yarns fusing together and more durable after curing,although the entire system remains breathable.

Although the present invention has been described in considerable detailwith reference to certain preferred versions thereof, other versions arepossible. Therefore, the spirit and scope of the appended claims shouldnot be limited to the description of the preferred versions containedherein. All features disclosed in this specification may be replaced byalternative features serving the same, equivalent or similar purpose,unless expressly stated otherwise. Thus, unless expressly statedotherwise, each feature disclosed is one example only of a genericseries of equivalent or similar features.

What is claimed is:
 1. A breathable, multi-component exhaust insulationsleeve, said insulation sleeve comprising: an inner layer comprising abraided or knit fabric made from a first high-temperature resistantmaterial; and an outer cover layer comprising a circular knitted fabricincluding glass fibers and thermoplastic resin-based fibers; whereinsaid insulation sleeve may be disposed about an outer surface of asection of pipe used to transport exhaust gases.
 2. The insulationsleeve set forth in claim 1, wherein said inner layer is made frommaterial selected from the group consisting of e-glass, s-glass, silica,basalt and ceramic.
 3. The insulation sleeve set forth in claim 1,wherein said outer cover layer is made from a core spun yarn having aglass filament core and a thermoplastic fiber wrapped around said glassfilament core.
 4. The insulation sleeve set forth in claim 3, whereinsaid thermoplastic fiber is selected from the group consisting ofPoly(p-phenylene sulfide), Polyetherimide, Polyether ether ketone,Polysulfone, Polyphthalamide, nylon, polyester, and polypropylene. 5.The insulation sleeve set forth in claim 1, further including at leastone middle layer disposed between said inner layer and said outer layer.6. The insulation sleeve set forth in claim 5, wherein said middle layeris a metal foil layer.
 7. The insulation sleeve set forth in claim 6,wherein said metal foil layer includes a series of perforations.
 8. Theinsulation sleeve set forth in claim 6, wherein said metal foil layer ismade from a material selected from the group consisting of aluminum,fiberglass reinforced aluminum, stainless steel, nickel, copper and tin.9. The insulation sleeve set forth in claim 6, wherein said metal foillayer is over-wrapped with a high-temperature tape made from materialsselected from the group consisting of fiberglass, PPS, PEI, PI, PPA,nylon, polyester and polypropylene.
 10. The insulation sleeve set forthin claim 6, wherein said metal foil layer includes a film disposed on atleast one side of said metal foil layer, wherein said film ismanufactured from material selected from the group consisting ofPoly(p-phenylene sulfide), Polyetherimide, Polyether ether ketone,Polysulfone, Polyphthalamide, nylon, polyester and polypropylene
 11. Theinsulation sleeve set forth in claim 1, wherein said outer cover layeris treated with a fluorocarbon.
 12. The insulation sleeve set forth inclaim 1, wherein said inner layer is formed from braided silica, andwherein said sleeve further comprises at least one layer of braidedfabric including e-glass fibers.
 13. The insulation sleeve set forth inclaim 12, wherein said outer cover layer is formed from PPS/glassfibers.
 14. The insulation sleeve set forth in claim 13, wherein saidouter cover layer is sewn into a tubular sleeve using a high temperaturesewing thread made from material selected from the group consisting ofglass/stainless steel, meta aramid and para-aramid.
 15. The insulationsleeve set forth in claim 14, wherein said outer cover layer is sewninto said tubular sleeve with a safety lock stitch.
 16. The insulationsleeve set forth in claim 12, further including a second layer of saidbraided e-glass fibers, which is disposed about the outside of said atleast one layer of said braided e-glass fibers.
 17. The insulationsleeve set forth in claim 16, further including a metal foil layerdisposed about the outer surface of said second layer of said braidede-glass fibers.
 18. The insulation sleeve set forth in claim 17, whereinsaid metal foil layer comprises fiberglass reinforced aluminum.
 19. Theinsulation sleeve set forth in claim 18, wherein said metal foil layerincludes a series of perforations.
 20. The insulation sleeve set forthin claim 17, further including a tape wrap disposed about an outersurface of said metal foil layer.